Previous   |   Next

doi:10.2204/iodp.proc.317.104.2011

Site U1352¹

Expedition 317 Scientists²

Background and objectives

Hole U1352A

• Position: 44°56.2440′S, 172°1.3615′E

• Start hole: 1145 h, 30 November 2009

• End hole: 1530 h, 30 November 2009

• Time on hole (d): 0.16

• Seafloor (drill pipe measurement from rig floor, m DRF): 354.8 (APC mudline)

• Distance between rig floor and sea level (m): 11.0

• Water depth (drill pipe measurement from sea level, m): 343.8

• Total depth (drill pipe measurement from rig floor, m DRF): 397.0

• Total penetration (m DSF): 42.2

• Total length of cored section (m): 42.2

• Total core recovered (m): 43.92

• Core recovery (%): 104

• Total number of cores: 5

Hole U1352B

• Position: 44°56.2558′S, 172°1.3630′E

• Start hole: 1530 h, 30 November 2009

• End hole: 1615 h, 5 December 2009

• Time on hole (d): 5.03

• Seafloor (drill pipe measurement from rig floor, m DRF): 354.6

• Distance between rig floor and sea level (m): 11.0

• Water depth (drill pipe measurement from sea level, m): 343.6

• Total depth (drill pipe measurement from rig floor, m DRF): 1185.5

• Total penetration (m DSF): 830.9

• Total length of cored section (m): 830.9

• Total core recovered (m): 613.87

• Core recovery (%): 74

• Total number of cores: 94

Hole U1352C

• Position: 44°56.2662′S, 172°1.3630′E

• Start hole: 2015 h, 5 December 2009

• End hole: 2200 h, 20 December 2009

• Time on hole (d): 15.07

• Seafloor (drill pipe measurement from rig floor, m DRF): 354.5 (tagging seafloor)

• Distance between rig floor and sea level (m): 11.0

• Water depth (drill pipe measurement from sea level, m): 343.5

• Total depth (drill pipe measurement from rig floor, m DRF): 2282.0

• Total penetration (m DSF): 1927.5

• Total length of cored section (m): 1296.4

• Total core recovered (m): 655.02

• Core recovery (%): 51

• Total number of cores: 146

Hole U1352D

• Position: 44°56.2326′S, 172°1.3611′E

• Start hole: 0615 h, 21 December 2009

• End hole: 2100 h, 21 December 2009

• Time on hole (d): 0.61

• Seafloor (drill pipe measurement from rig floor, m DRF): 345.2 (APC mudline)

• Distance between rig floor and sea level (m): 11.0

• Water depth (drill pipe measurement from sea level, m): 344.2

• Total depth (drill pipe measurement from rig floor, m DRF): 472.2

• Total penetration (m DSF): 127.0

• Total length of cored section (m): 127.0

• Total core recovered (m): 130.84

• Core recovery (%): 103

• Total number of cores: 14

Integrated Ocean Drilling Program (IODP) Site U1352 (proposed Site CB-04B) is located on the upper slope (344 m water depth) within the Canterbury Bight and is the most basinward site of the Canterbury Basin drilling transect. This location was chosen as a primary site in response to an Environmental Protection and Safety Panel (EPSP) request (December 2005) to avoid the high seismic amplitudes observed at 1.6–1.7 s two-way traveltime at Site CB-04A. Site U1352 is located downdip from Site CB-04A on dip seismic Profile EW00-01-60 (Figs. F1, F2). Because of the move from Site CB-04A, there is no crossing strike profile at Site U1352.

Site U1352 penetrates seismic sequence boundaries U6–U19 where sediments are finer grained and pelagic microfossils are more abundant than at shelf sites. This provides good age control for sequences drilled on the shelf.

An additional target, requiring deep penetration, was the Marshall Paraconformity, which has been dated at its onshore type section using strontium isotopes as representing a hiatus of ~3.4 m.y. (32.4–29 Ma) (Fulthorpe et al., 1996). The paraconformity probably records intensified current erosion or nondeposition at all water depths that accompanied the development of ocean circulation following the opening of the seaway south of Tasmania (Carter, 1985; Fulthorpe et al., 1996; Carter et al., 2004). Seismic interpretation supports a current-related origin by indicating that the paraconformity forms the base of the interval of sediment drift deposition. Indeed, immediately post–Marshall Paraconformity sedimentation involves sediment drift deposition in shallow (Ward and Lewis, 1975), intermediate (Fulthorpe and Carter, 1991; Lu et al., 2003), and deep water settings (Shipboard Scientific Party, 1999a; Carter et al., 2004). Drilling during Ocean Drilling Program (ODP) Leg 181 indicates that the paraconformity developed in deep (bathyal) water ~1–2 m.y. earlier than in shallow water (McGonigal and Di Stefano, 2002). Dating the paraconformity in the offshore Canterbury Basin at Site U1352 provides a further test of this hypothesis.

Because of time constraints, drilling into one of the large elongate sediment drifts of the Canterbury Basin, specifically drift D11 (Lu et al., 2003; Lu and Fulthorpe, 2004), became a secondary objective. Therefore, sites that were originally proposed for drilling into drift D11 (proposed Sites CB-05B to CB-05E) became contingency sites to be drilled only if drilling at shelf sites was not possible. Nevertheless, insights into sediment drift deposition and paleoceanography are expected from drilling at Site U1352. The largest mounded elongate drifts lie within the northeastern part of the shelf-slope sediment prism. Drift geometries become gradually less pronounced along strike toward the southwest, and mounded drifts are absent at Site U1352 (Lu and Fulthorpe, 2004). However, the generation of mounded drifts requires specific conditions that are not well understood; a slope contour current alone is insufficient, as indicated by the fact that such drifts are not forming under the present current regime. Current reworking of sediments is evident at Site U1352, and currents may have left a paleoceanographic record of glacial–interglacial cycles, as at ODP Site 1119 (Carter et al., 2004), without producing distinctive geometries.

The principal objectives at Site U1352 were

1. To sample slope sediments basinward of clinoform breaks of progradational seismic sequence boundaries, particularly U6–U9, U11, and U13–U19 (late Miocene to Pleistocene) to provide sequence boundary ages;

2. To penetrate the Marshall Paraconformity and the top of the underlying Amuri Limestone (late Eocene at total depth); and

3. To provide insights into the role of contour current deposition in a location where prominent sediment drift geometries are absent.

¹Expedition 317 Scientists, 2011. Site U1352. In Fulthorpe, C.S., Hoyanagi, K., Blum, P., and the Expedition 317 Scientists, Proc. IODP, 317: Tokyo (Integrated Ocean Drilling Program Management International, Inc.). doi:10.2204/iodp.proc.317.104.2011

²Expedition 317 Scientists' addresses.

Publication: 4 January 2011
MS 317-104

Top of page   |   Previous   |   Next